The present invention generally relates to motion control apparatus and in particular brakes, specifically relates to brakes for linear motion applications, and more specifically relates to linear motion brakes having special application to power-off situations.
The popularity of linear motion devices in the machine tool, semiconductor, and medical industries has been increasing as the result of their ability to move a load in a linear movement direction to a position with extreme accuracy and at very high speeds. However, problems have been encountered in stopping linearly moving loads especially in the event of a power outage. Specifically, as movement and positioning of the load is dependent upon current being supplied to the linear motor, loads carried by linear motion devices will move under gravitational and/or inertia forces in the event that current is interrupted to the linear motor such as the result of a power outage. This problem is also enhanced in linear motion devices because of the use of high performance linear bearings which minimize sliding friction.
Although marketing of linear motion device packages is increasing in popularity, often the end user purchases the various components of linear motion devices such as linear bearings, armatures and magnet tracks or stators, and position feedback devices and arranges such components according to their particular application. Thus, linear motion devices have a variety of configurations.
Although linear motion brakes have been utilized in other fields such as roller coasters, attempts to provide brakes for stopping linear motion of loads driven by linear motion devices have not been commercially viable, possibly due to their relative small size.
Thus, a need exists for a brake for stopping linearly moving loads and especially for use with linear motion devices and particularly for use in stopping linearly moving loads in the event of a power outage, emergency stop, parking, or similar situation. In a preferred aspect, the linear motion brake must be adaptable for use with any configuration of a linear motion device and in most preferred aspects is modular in form for attachment to the linear motion device if and when braking is desired in the particular application of the linear motion device.
The present invention solves these needs and other problems in the field of brakes for linear motion applications by providing, in the preferred form, a brake having special application for use with a linear motion device. In preferred aspects, at least a first friction element and a U-shaped track are spaced from and parallel to the linear bearings and the armature and stator of the linear motion device, with the first friction element located within the U-shaped track and being movable between an engaged position engaging with the U-shaped track and stopping movement of the sliding plate relative to the base plate and a disengaged position which does not impede movement of the sliding plate relative to the base plate. In most preferred aspects of the present invention, the linear motion brake is located outside of the linear motion device spaced in a direction generally perpendicular to the linear movement direction and in the preferred form parallel to the linear motion device but offset from the linear motion device. In other aspects, a channel including the U-shaped track and a tape seal defines a hollow interior, with the body to which the friction element is moveably mounted including a slot slideably receiving the tape seal with linear motion of the sliding plate relative to the base plate.
In other preferred aspects of the present invention, the actuator element which moves the carrier for an interface element between an engaged and disengaged position is moveably mounted in the axial bore of a body allowing self-centering of the actuator element in the axial bore in non-axial directions.
Still in other aspects of the present invention, the carrier for an interface element is biased into a cross bore by a spring sandwiched between a stop in the cross bore and the carrier. In further aspects of the present invention, the actuator element which moves the carrier for an interface element between an engaged and disengaged position is received in a diametric groove of the carrier for preventing rotation of the carrier in the cross bore of the body.
It is thus an object of the present invention to provide a novel apparatus for controlling motion.
It is further an object of the present invention to provide such a novel motion controlling apparatus stopping linear motion.
It is further an object of the present invention to provide such a novel motion controlling apparatus having special application for use with a linear motion device.
It is further an object of the present invention to provide such a novel motion controlling apparatus for use in the event of a power outage, emergency stop, parking or similar situation.
It is further an object of the present invention to provide such a novel motion controlling apparatus adaptable for use with any configuration of linear motion device.
It is further an object of the present invention to provide such a novel motion controlling apparatus of a modular form.
It is further an object of the present invention to provide such a novel motion controlling apparatus applying a constant engagement force at any position in the linear movement direction.
It is further an object of the present invention to provide such a novel motion controlling apparatus having a small cross sectional size in directions perpendicular to the linear movement direction.
It is further an object of the present invention to provide such a novel motion controlling apparatus utilizing mechanical advantage to reduce the input power requirements.
It is further an object of the present invention to provide such a novel motion controlling apparatus easily adaptable to utilize different types of actuators.
It is further an object of the present invention to provide such a novel motion controlling apparatus formed of relatively few easily manufactured and assembled components.
It is further an object of the present invention to provide such a novel motion controlling apparatus having minimal effect on the dynamics of the linear motion.
It is further an object of the present invention to provide such a novel motion controlling apparatus minimizing side loading of the linear bearings of a linear motion device.